Anesthesia-Strauss Flashcards
methods of administration for inhalationals
- nasal hood for oral procedures
- full face mask for short procedures outside face
- LMA (laryngeal mask anesthetic) for longer procedures
- endotracheal inbubations for longer procedures (goes between vocal cords)
what is MAC?
minimum alveolar concentration
-concentration of an anesthetic at which 50% of patients will not respond to a noxious stimulus
How much ‘MAC’ is given for induction vs maintenance?
-induction 2-3 MAC and maintenance usually 0.5-1.5 MAC
what are the stages of anesthesia?
Guedel’s stages (based on ether)
- stage I Analgesia
- II excitement
- III surgical Anesthesia (surgery here)
- IV Apnea (can die here)
blood gas solubility
- this coefficient represents the ability of an agent to dissolve in blood
- only drugs NOT dissolved can see the brain, so the lower the BGS the faster the rise in arterial gas tension
- also shows speed of recovery
examples of some of the minor inhalational agents
- ethyl chloride
- chloroform
- diethyl ether
- methoxyflurane
- nitrous oxide (not potent, but hardly minor)
what inhalational agent shows liver toxicity?
halothane
which inhalational agent has some seizure activity?
enflurane
which agent has the lowest blood gas solubility?
Desflurance
-BGS 0.42
pungent odor, so not well tolerated by airway for indution-breath holding, coughing and laryngospasm
Desflurane
desflurance
-Requires special vaporizer (expensive)
-Lowest B/G solubility of all (0.42) so
very fast in and out
-Pungent odor so not well tolerated by airway for induction-breath holding, coughing and laryngospasm
-High MAC of 6%
-Causes tachycardia so no change in
cardiac output
-Fast shallow breathing with inc PaCO2
-greenhouse gas
Isoflurane
-Introduced in 1981
-MAC is 1.2%
-Moderately low BGS so relatively fast in and out
-Pungent ether-like odor so no induction
-Minimal cardiac depression via inc in
HR of 10% (less than Des)
-Good bronchodilator
-Slight metabolism in liver but small (0.17%)
-Good muscle relaxation
which agent is a good bronchodilator
isoflurane
- Newest agent now!
- Very low BGS (near N2O)
- Very little irritation so can breathe the patient down
- MAC 1.71%
- Great in OMS outpt anesthesia by itself
- Mild negative inotrope and no tachycardia. CO drops slightly more than others
- VT drops and rate slightly
- 5% metabolism but not toxic
- Must have high flow to prevent Compound A toxicity
Sevoflurane
-“the workhorse”
properties of narcotics (IV)
- all are analgesic
- varying effect on other receptors
- all are addicting and induce tolerance
- main effect is reaction to pain
- lesser effect on perception of pain
- all are respiratory depressants
- all cause some nausea
- all are constipating
- relief is better with severe, sharp pain rather than constant dull pain
divisions of narcotics
- opiates: morphine, codeine
- synthetic opiates: dilaudid, heroin
- opiods (synthetic compounds): fentanyl, demerol, alphaprodine
patient has pin point pupils, what is that called and what are they probably on?
-meiosis (opposite would be midriasis), and meiosis is a mallmark of morphine
what narcotic is good for MI patients?
morphine
example of synthetic opiod
demerol, fentanyl (sublimaze)
demerol
- makes the patient have a sympathetic response (I think)
- shows anticholinergic effects
- duration 3-4 hr IM, 30-60 min IV
- good for postop analgesic but fair for sedation, OPD GA
synthetic opiod that is used a lot
- it’s a potent narcotic: 100X morphine
- fast onset (3 min), short duration (15-30 min IV); good for OPD
fentanyl (sublimaze)
“stiff chest syndrome”
-what is it, and what causes it?
caused when over 100 mcg of fentanyl (sublimaze) is given. It doesn’t happen to everyone, but their chest becomes rigid and you can’t even ventilate them
- sedative-hypnotics
- relaxation and reduction of anxiety
- act on limbic system and lesser extent on RAS
- increase GABA levels locally in these systems
Benzodiazepines (given IV)
examples of benzodiazaepines and their duration of action
- Long acting (20-80 hours): diazepam (valium)
- medium acting (10-20 hrs): lorazepam
- short acting (2-5 hrs): midazolam (versed) and triazolam (halcion)
Benzodiazepines
- effect on limbic, RAS (renin-angiotensin system)
- sedative, hypnotics
- powerful anxiolytic
- generally good anticonvulsants
- all are cardiac and ventilatory depressants
- good muscle relaxants
- all lead to dependence, tolerance
- can see paradoxical (opposite of expected) reactions
Valium vs Versed
Diazepam vs Midazolam
Versed is about twice as strong (potent) as Valium, but has a smaller therapeutic index so it’s more dangerous
Versed more: potent, anterograde amnesia, resp depression
Valium more: injection pain,/ vein inflammation (thrombo?) and longer duration
active metabolites of benzodiazepines
- I think these are specifically referring to valium and versed
- oxazepam-Serax
- desmethydiazepam
- apha 1-hydroxymidazolam
what is the principal mechanism of barbiturates?
re-distribution
three categories of barbiturates
- ultra-short acting (thio, metho)
- short acting (nembutal, seconal)
- long acting (amytal, phenobarbital)
what drugs discussed are metabolized by the liver and to what extent?
-Barbiturates: 20%/hr
which drug is an anti-analgesic at low doses?
barbiturates
-they actually make the pain worse at low dose
patient has Acute intermittent porphyria…
don’t give them barbiturates
contraindications for barbiturates
- allergic
- acute intermittent porphyria
site of action of barbiturates
Reticular activating system (RAS)
thiopental (Pentothal)
- a barbiturate
- main use is as induction agent in GA (3-4 mg/kg)
- may see severe histamine release
- sedation dose: 20-50 mg total
truth serum
thiopental in sedation dose (20-50 mg)
examples of barbiturates
- thiopental (Pentothal)
- methohexital (Brevital)
- most common agent on OMFS due to short onset and quick duration of action
- 3X more potent than pentothal (thiopental)
- induction dose=1 mg/kg
- may cause shakes
- intermittent injection technique
methohexital (Brevital)
-Brevital shakes
Brevital respiratory and cardiac effects
Respiratory -dose-dependant depression -hiccups common -can obtund laryngeal/pharyngeal reflexes -increased rate-decreased tidal vol Cardiac -increased HR -decreased PVR and BP
similar to brevital, but non-barbiturate inducing agent
- white milky, viscous material
- injection burns-lidocaine
Propofol (Diprivan)
-used instead of barbiturates
induction agent
- phencyclidine derivative (non-narcotic, non-barb, rapid acting)
- profound analgesia
- patient doesn’t appear asleep
- DVS-inc HR and BP
Ketamine
-“special K”
when is ketamine contra indicated?
epilepsy or hypertension
what drugs are the anticholinergics?
- Atropine
- Robinul (glycopyrrolate)
vagolytic effect on heart rate and secretions
-used in OMFS for secretions and in kids for HR
atropine
-drying/HR ratio increased
Robinul (glycopyrrolate)
